I think it is mainly seasonal.
In fact, a contraction in Q1 after Q4 is quite common, so one could argue that the world market is ahead of the game with a 0.4 percent quarterly sequential growth.
Although Japan is not doing well on a sequential or year-on-year basis this cannot be much to do with the earthquake of March 11. The generation of March numbers by averaging January, February and March minimizes that effect.
However, the apparent downward revision of February averaged sales is a concern. I await updated WSTS numbers.